Pitch control assembly

ABSTRACT

A method of controlling a propeller assembly, having a blade, piston end cap, and piston, with a pitch control unit, having a transfer bearing and a blade angle unit, the method comprising: axially moving a transfer tube relative to and circumscribing the transfer bearing, sensing an axial movement of the transfer tube with the blade angle unit.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 15/027,801, filed Apr. 7, 2016, and now allowed, which claimspriority to the prior filed, PCT Application Serial No. PCT/GB13/052602,filed Oct. 7, 2013, both of which are incorporated herein by referencein their entirety.

BACKGROUND

Contemporary propeller assemblies may have a means of varying the bladepitch via a pitch control unit (PCU), to optimize efficiency of thrustdelivery. In this manner, the propeller may be designed to vary pitch inflight, to give optimum thrust, from takeoff and climb to cruise.Varying the pitch angle may allow the aircraft to maintain an optimalangle of attack or maximum lift to drag ratio on the propeller blades asaircraft speed varies.

BRIEF DESCRIPTION

In one aspect, the disclosure relates to a method of controlling apropeller assembly, having a blade, piston end cap, and piston, with apitch control unit, having a transfer bearing and a blade angle unit,the method comprising: axially moving a transfer tube relative to andcircumscribing the transfer bearing, sensing an axial movement of thetransfer tube with the blade angle unit, where the blade angle unitcomprises a series of coils radially spaced from and circumscribing atleast a portion of the transfer tube, and determining a pitch angle ofthe blade based on the sensed movement of the transfer tube.

In another aspect the disclosure relates to a method of adjusting apitch angle of a blade with a pitch control unit having a transferbearing and a blade angle unit, the method comprising: axially moving atransfer tube relative to and circumscribing the transfer bearing,sensing an axial movement of the transfer tube with the blade angleunit, where the blade angle unit comprises a series of coils radiallyspaced from and circumscribing the transfer tube, determining the pitchangle of the blade based on the sensed movement, and outputting a pitchangle value.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic view of an aircraft having variable pitchpropellers.

FIG. 2 is a schematic view of a propeller assembly having a variablepitch propeller.

FIG. 3 is a schematic illustration of an exemplary variable pitchpropeller assembly and a prior art pitch control unit.

FIG. 4 is a cross-sectional view of the prior art pitch control unitillustrated in FIG. 3.

FIG. 5 is a cross-sectional view of a pitch control assembly accordingto various aspects described herein.

FIG. 6 is a schematic illustration of the pitch control assembly of FIG.5 included within an exemplary variable pitch propeller assembly.

DETAILED DESCRIPTION

FIG. 1 illustrates an aircraft 8 having multiple propeller assemblies 10each having a hub 12 and multiple blades 14. While one example of anaircraft has been illustrated it will be understood that any suitableaircraft may utilize embodiments of the innovation described herein.FIG. 2 schematically illustrates a propeller assembly having a hub andonly a single blade illustrated. While a plurality of circumferentiallyspaced blades 14 may be supported within the hub 12 as illustrated inFIG. 1, only one blade is illustrated in the remaining figures forclarity purposes. As illustrated in FIG. 3, the hub 12 and the multipleblades 14 may be operably coupled to a suitable propulsion plant, suchas an engine 20, through a drive shaft 22 and a gearbox 24. Asillustrated, the propeller assembly 10 may be mounted on the propellergearbox 24. An accessory gear box 26 and a generator 28 are alsoillustrated as being located adjacent the propeller assembly 10 andpitch control unit 30.

Each blade 14 may be adjustable for pitch during rotation of thepropeller assembly 10 under the control of a pitch control unit (PCU)30; a prior art PCU 30 is schematically included in FIG. 3. Hydrauliclines may be ported along a hydraulic transfer tube arrangement 32 fromthe PCU 30 mounted on the back of the gearbox 24. The PCU 30 houses ahydraulic transfer bearing 34 and a blade angle unit 36. Conventionally,the hydraulic transfer bearing 34 and the blade angle unit 36 are placedin series resulting in considerable unit length. The PCU 30 may alsoinclude a number of control valves 38 that may allow hydraulic fluid tobe transferred through the hydraulic transfer tube arrangement 32 toportions of a piston end cap 40.

The piston end cap 40 houses a piston 42, which may be moved dependingon where hydraulic fluid is introduced into the piston end cap 40. Forexample, if hydraulic fluid is introduced into a first portion 44 of thepiston end cap 40 the piston 42 is moved towards a fine pitch direction,which reduces a pitch of the blades 14. Conversely, if hydraulic fluidis introduced into a second portion 46 of the piston end cap 40 thepiston 42 is moved towards a coarse pitch direction, which increases thepitch of the blades 14. As the piston 42 moves, the propeller hub 12 ismoved backwards and forwards and the pitch of the blades 14 attachedthereto are moved.

As illustrated more clearly in FIG. 4, the prior art propeller PCU 30houses the hydraulic transfer bearing 34 and the blade angle unit 36 inseries. The PCU 30 may include a housing 50 that extends around at leasta portion of the hydraulic transfer bearing 34 and the blade angle unit36. The conventional PCU 30 may be approximately 14 inches in length.Hydraulic lines 52 may be included within the housing 50 and may befluidly coupled to hydraulic lines 54 within the hydraulic transferbearing 34. The blade angle unit 36 may include a series of coils 60that may measure a magnetic core sleeve 62 located on at least a portionof the hydraulic transfer bearing 34. In this manner, the blade angleunit 36 may measure the axial position of the end of the hydraulictransfer bearing 34 and the propeller blade angle may be calculatedtherefrom.

FIG. 5 illustrates one embodiment of a pitch control assembly (PCU) 110according to the innovation, which provides a relatively compact length,unlike the prior art, sequentially arranged PCU 30. As seen in thecross-sectional view of FIG. 5, the pitch control assembly 100 includesa pitch control unit 102 having a housing 104, with a plurality ofcontrol valves 106 and corresponding hydraulic lines 108 located withinthe housing 104. A blade angle unit 110 may include a series of coils112 located within the housing 104. At least a portion of the series ofcoils 112 may be located within the housing 104 including that theentire series of coils 112 may be located within the housing 104.

A transfer bearing 120 may be mounted to the housing 104 and have atleast a portion located within the transfer tube 140. A plurality ofhydraulic lines 122 within the transfer bearing 120 may be fluidlycoupled to the hydraulic lines 108 of the pitch control unit 102.

The hydraulic lines 108 within the housing 104 and the hydraulic lines122 within the transfer bearing 120 may include at least a finehydraulic line and a coarse hydraulic line. In the illustrated example,a ground fine hydraulic line for reducing the pitch of the blades 14when the aircraft 8 is on the ground, a flight fine hydraulic line forreducing the pitch of the blades 14 when the aircraft 8 is in flight,and a coarse hydraulic line for increasing the pitch of the blades 14have been included.

The transfer bearing 120 may be formed in any suitable manner includingthat it may include a mandrel 124. The hydraulic lines of the transferbearing 120 may be located internally of the mandrel 124. The mandrel124 may have one end 126 mounted to the housing 104 to mount thetransfer bearing 120 to the housing 104. By way of non-limiting example,an axial adjuster 128 may mount the mandrel 124 to the housing 104 toenable relative axial movement of the mandrel 124 and the housing 104.This may provide a quick and simple propeller rigging feature that ismuch faster than the conventionally way, which is achieved by anadjustment procedure that includes removal of the propeller spinner andthe pitch change piston end cap and requires a much longer period oftime. By way of further example, the axial adjuster 128 may include athreaded end on the mandrel 124 passing through an opening 130 in thehousing 104 and a lock nut 132 threaded onto the threaded end to lockthe mandrel 124 relative to the housing 104. While the mandrel 124 isillustrated as including a smooth end it will be understood that the end126 of the mandrel 124 may be threaded.

A transfer tube 140 may axially receive and be axially moveable relativeto at least a portion of the transfer bearing 120. The transfer tube 140may both rotate and translate around the mandrel 124. More specifically,the axial movement of the transfer tube 140 may result in its rotation.A magnetic core sleeve 150 may be carried by the transfer tube 140 andmay be located within the series of coils 112. The magnetic core sleeve150 may be carried by the transfer tube 140 in any suitable mannerincluding that the magnetic core sleeve 150 may fit onto a portion ofthe transfer tube 140. Thus, the magnetic core sleeve 150 moves with thetransfer tube 140. As illustrated, at least a portion of each of thetransfer bearing 120, the transfer tube 140, and the magnetic coresleeve 150 may be located within the series of coils 112. It iscontemplated that the entire magnetic core sleeve 150 may be locatedwithin the series of coils 112 throughout an operational axial range ofmovement of the transfer tube 140. Hydraulic lines 152 may be includedin the transfer tube 140 and may provide fluid to a piston end cap ofthe propeller assembly.

During operation, a pitch angle of the propeller may be controlled byaxially moving the transfer tube 140 relative to the transfer bearing120 in response to fluid supplied through the hydraulic lines 108, 122,and 152 in response to the actuation of the control valves 106, and theblade angle unit 110 senses the corresponding axial movement of themagnetic core sleeve 150 within the series of coils 112 and provides anoutput indicative of the amount of blade angle movement. Morespecifically, the series of coils 112 may measure the magnetic coresleeve 150 mounted on the transfer tube 140. In this manner, the bladeangle unit 110 may measure the axial position of the end of the transferbearing 140 and the propeller blade angle may be calculated therefrom.In this manner, the feedback feature may be positioned around thetransfer tube 140 instead of being on the end such that the length ofthe pitch control assembly 100 is almost halved compared to conventionalPCUs. It will be understood that the pitch control assembly 100 may belocated adjacent the propeller gearbox and may be incorporated into anysuitable propeller assembly including the propeller assembly previouslydescribed above. FIG. 6 illustrates the pitch control assemblyincorporated into the propeller assembly previously described forexemplary purposes. Thus, during operation, fluid may be providedthrough hydraulic lines 108, 122, and 152 such that hydraulic fluid isintroduced into either the first portion 44 of the piston end cap 40 andthe piston 42 is moved towards a fine pitch direction, which reduces apitch of the blades 14 or hydraulic fluid is introduced into the secondportion 46 of the piston end cap 40 and the piston 42 is moved towards acoarse pitch direction, which increases the pitch of the blades 14. Asthe piston 42 moves, the transfer tube 140 moves axially in the samedirection around the mandrel 124.

As may also be seen in FIG. 6, the length of the pitch control assembly100 is much shorter than that of the prior art unit and may beapproximately 8 inches in length. This allows for a larger generator 28to be included in the nacelle. This may prove beneficially as aircraftare demanding more electrical power to be generated by the propulsionsystem. Such an increase may otherwise be difficult to accommodatewithin the engine nacelle.

The embodiments described above provide for a variety of benefitsincluding that the length of the assembly is much shorter thanconventional units, which offers significant advantages in terms ofsystem installation and weight. As compared to conventional PCUs,embodiments of the innovation allow the electromagnetic blade angle unitcoils to be placed around the inverted hydraulic transfer bearing, whichalmost halves the length of the assembly. As the pitch control assemblyis subject to an aggressive vibration field, the shorter length isbetter suited to this environment, as it is less susceptible tovibration, and results in increased reliability. Further, embodiments ofthe innovation also dramatically reduce hydraulic transfer bearingrigging procedure as the embodiments allow quick, external access forrigging, which significantly reduces maintenance costs. Contemporarypropeller systems locate the propeller rigging adjuster on the propellercrosshead at the front of the propeller, which requires the propellerspinner and the piston end cap to be removed for access. Embodiments ofthe innovation allow rigging to be undertaken on the end of the pitchcontrol unit and provide a simple external adjustment.

This written description uses examples to disclose the innovation,including the best mode, and also to enable any person skilled in theart to practice the innovation, including making and using any devicesor systems and performing any incorporated methods. The patentable scopeof the innovation is defined by the claims, and may include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal languages of the claims.

What is claimed is:
 1. A method of controlling a propeller assembly,having a blade, piston end cap, and piston, with a pitch control unit,having a transfer bearing and a blade angle unit, the method comprising:axially moving a transfer tube relative to and circumscribing thetransfer bearing, sensing an axial movement of the transfer tube withthe blade angle unit, where the blade angle unit comprises a series ofcoils radially spaced from and circumscribing at least a portion of thetransfer tube, and determining a pitch angle of the blade based on thesensed movement of the transfer tube.
 2. The method of claim 1, furthercomprising comparing the pitch angle to a required pitch angle.
 3. Themethod of claim 2, further comprising actuating a control valve tosupply a fluid into the transfer bearing to adjust the pitch angle ofthe blade.
 4. The method of claim 3, further comprising flowing thefluid to a first portion of the piston end cap to move the piston towarda coarse pitch direction.
 5. The method of claim 3, further comprisingflowing the fluid to a second portion of the piston end cap to move thepiston toward a fine pitch direction.
 6. The method of claim 3, whereinsupplying a fluid further comprises supplying a fluid through at leastone hydraulic line disposed within the transfer bearing.
 7. The methodof claim 6, wherein the transfer bearing includes a mandrel and the atleast one hydraulic line is disposed within the mandrel.
 8. The methodof claim 1, further sensing with the blade angle unit a magnetic fieldbetween a magnetic element carried by the transfer tube and the seriesof coils.
 9. The method of claim 8, further comprising determining withthe blade angle unit an axial movement of the magnetic element withrespect to the series of coils.
 10. The method of claim 8, wherein atleast a portion of each of the transfer bearing, transfer tube, andmagnetic element is within the series of coils.
 11. The method of claim10, wherein an entire body of the magnetic element is located within theseries of coils throughout an operational axial range of movement of thetransfer tube.
 12. The method of claim 1, further comprising rotatingthe transfer tube as a result from the axial movement of the transfertube.
 13. A method of adjusting a pitch angle of a blade with a pitchcontrol unit having a transfer bearing and a blade angle unit, themethod comprising: axially moving a transfer tube relative to andcircumscribing the transfer bearing, sensing an axial movement of thetransfer tube with the blade angle unit, where the blade angle unitcomprises a series of coils radially spaced from and circumscribing thetransfer tube, determining the pitch angle of the blade based on thesensed movement, and outputting a pitch angle value.
 14. The method ofclaim 13, further comprising comparing the pitch angle value to arequired pitch angle.
 15. The method of claim 14, further comprisingactuating a control valve for supplying a fluid into the transferbearing to adjust the pitch angle of the blade.
 16. The method of claim15, wherein supplying a fluid further comprises supplying a fluidthrough at least one hydraulic line disposed within the transferbearing.
 17. The method of claim 16, wherein the transfer bearingincludes a mandrel and the at least one hydraulic line is disposedwithin the mandrel.
 18. The method of claim 13, further comprisingdetermining with the blade angle unit an axial movement of a magneticelement carried by the transfer tube with respect to the series ofcoils.
 19. The method of claim 18, wherein at least a portion of each ofthe transfer bearing, transfer tube, and magnetic element is within theseries of coils.
 20. The method of claim 10, wherein an entire body ofthe magnetic element is located within the series of coils throughout anoperational axial range of movement of the transfer tube.